The present invention relates generally to power systems in vehicles. More specifically, the present invention relates to a power system having both a standard mode and an electrified mode to operate engine accessories.
Automotive vehicles typically have a drive system for powering engine accessories such as alternators, water pumps, air conditioning compressors, power steering pumps, radiator cooling fans, etc. The drive system is powered by torque from a pulley mounted on the crankshaft on an engine. The crankshaft converts the reciprocal motion of the engine's pistons into a rotational motion, which in turn, rotates the pulley and drives an accessory belt. The accessory belt winds through the various engine accessories providing them with mechanical power.
Powering the accessories is a secondary function of the engine, the primary function of the engine being providing power for propulsion. In many cases, the conventional drive system is inadequate to supply power to the various accessories. One situation in which the conventional drive system is inadequate is when the vehicle is stationary. In this situation, the engine must run at an idle to provide power to the accessories.
A second situation in which the conventional drive system is inadequate is when the vehicle propulsion requires an extreme load on the engine, and the engine cannot provide adequate power to both propel the vehicle and power the accessories. An example of an extreme loading on the engine is when the vehicle is climbing a hill with the accessories running. Under these circumstances, the loading applied to the engine for powering the accessories is called a “parasitic” loading because it can negatively impact the amount of power delivered for propulsion. Currently, engines are “sized up” to be large enough to deliver adequate power for propulsion and for accessories.
Thus, there is a need for a drive system that provides an adequate amount of power to both engine propulsion and engine accessories.
There is also a need for a drive system that powers accessories when the vehicle is stationary and without requiring the engine to idle.
There is a further need for a drive system that removes parasitic loading on the engine when it is under heavy loads.